Method of producing metals



J1me 1954 a. BERGHAUS ETAL 3,135,675

METHOD OF PRODUCING METALS 2 Sheets-Sheet 2 Filed July 14, 1959 FIG. 2

INVENTORS BERNHARD BERGHAUS MARIA STAESCHE ATTORNEYS June 2, 1964 B. BERGHAUS ETAL 3,135,675

METHOD OF PRODUCING METALS 2 Sheets-Sheet 1 Filed July 14, 1959 INVENTORS BERNHARD BERGHAUS MARIA STAESCHE ATTORNEYS United States Patent Oil ice $335,675 Patented June 2, 1964 3,135,675 lVIETI-IOD OF PRODUCING METALS Bernhard Berghaus, Grand Hotel Dolder, Zurich, Switzerland, and Maria Staesche, Mattenstrasse 31, Wettingen, Aargau, Switzerland Filed July 14, 1959, Ser. No. 827,070 Claims priority, application Switzerland July 14, 1958 9 Claims. (Cl. 204-164) The present invention relates to the production of metals from initial substances containing at least one metal halide.

Among the large number of known methods for producing metals there are some in which the metal is obtained from its halide by chemical or electrolytic means. It has also been attempted to process liquid or gaseous metal halides by electrical action and to obtain the metal involved. By Way of example, it has been proposed to obtain titanium from titanium tetrachloride by means of an electric are or by silent electrical discharges.

The present invention is concerned with the production of metals from their halides by means of a process performed in at least two stages. In the first stage, at least one metal halide is converted into a reactive intermediate product by means of nitrogenous and hydrogenous reagents which include mixtures of nitrogen and hydrogen and gaseous combinations thereof such as ammonia. In the second stage, a product which contains at least portions of free metal is obtained from the intermediate product either under the action of an ionized gaseous atmos'phere containing at least one of the components nitrogen and hydrogen, or by calcination followed immediately by electrolysis in a fused salt bath.

The method according to this invention is disclosed in greater detail in conjunction with FIGS. 1 and 2 of which each represents a basic diagram of a plant for the performance of the method according to the invention.

The details of the present method will first be described for the production of titanium from titanium tetrachloride, but the method is not limited thereto. It may, in a similar manner, be employed for the production of silicon from SiCl of vanadium from VCl of tin from SnCL, and of aluminum from AlCl The metal compounds containing chlorine may also be replaced by suitable metal compounds containing bromine, iodine and fluorine. In all cases, the production process must be performed in at least two stages, the first stage being designed to produce the reactive intermediate product, to which end the metal halide to be processed is treated with nitrogenous or hydrogenous reagents or a mixture thereof.

The performance of this first stage of the manufacturing process will first be disclosed in conjunction with the embodiment of a suitable plant represented in FIG. 1. The metal halide employed is, by way of example, titanium tetrachloride in liquid form, which is held in a tank and designated as 11. From this tank 10 and through a nozzle 12 the metallic compound 11 is injected as a fine liquid spray into container 13 by means'of gas pressure. The necessary gas under suitable pressure is supplied to the tank 10 via line 14. A gas, such as argon, must be selected which cannot react with the metallic compound 11 and which can act as a protective gas for the intermediate product obtained in the container 13. In the container 13 the finely dispersed titanium tetrachloride is intimately mixed with-a nitrogenous and hydrogenous atmosphere, e.g. with ammonia, which is blown upon the liquid jet via the inclined lines 15. This gas is supplied to the lines 15 via a control member 16 from tank 17. Ammonia may be replaced by another compound containing nitrogen and hydrogen, and for many metal halides a mixture of nitrogen gas and hydrogen gas may be employed for the production of the desired reactive intermediate product. The volume of gas supplied is advantageously so adjusted to the volume of the metal halide supplied that the solid intermediate product will absorb as large a portion of this gas as possible. The surplus gas is pumped from the container 13 through the connection 18, a comparatively small pump power being sufficient if the volumes of reagents supplied are suitably adjusted.

If titanium tetrachloride is sprayed through nozzle 12 and ammonia through lines 15, the resulting intermediate product will be a solid addition compound containing titanium, which will settle at the bottom of the container 13. If the volumes of reagents supplied are properly adjusted, the intermediate product will consist mainly of TiC1 .6NH

i.e. it will constitute an addition compound formed of titanium tetrachloride and ammonia. This intermediate product is stable if located in a suitable protective gas atmosphere. If desired, such a protective gas, e.g. argon, may be added to the gaseous reagent in the container 17 and be supplied to the reaction container 13 with the same. The protective gas should be selected so that it does not participate in the reaction in the container 13.

The solid intermediate product is removed from the lower portion of the container 13 by a suitable conveyor, by way of example the worm conveyor 21 driven by the shaft 20, and supplied to the processing station of the second production stage.

In order to obtain the free metal from this intermediate product, the latter is treated in an ionized gas atmosphere containing at least one of the components nitrogen and hydrogen. According to the processing conditions in this stage, a greater or lesser amount of free metal can be obtained from the intermediate product.

In the embodiment according to FIG. 1, the intermediate product obtained in the first stage is passed through the container 25 on an endless conveyor belt 24 running on rolls 22 and 23, collected'in the funnel 26 and removed from the container 25 by means of a suitable conveyor installation, such as the worm conveyor 28 driven by shaft 27. The product thereby obtainedin the present case will contain at least portions of free titanium metal.

During its passage through the container 25 the intermediate product on the conveyor belt 24 is subjected to the action of the ionized gas jets-29 blown into the said container 25, by way of example by a pump unit attached to the connection 31. As the whole inside of the container 25 is supplied only by the, gas jets 29 an ionized atmosphere is created which can act on the intermediate v product.

The gas jets 29 enter the metallic inner portion 32 via a nozzle-type bore, the said section 32 being electrically insulated from the metallic cover 34 of the container 25 by means of theinsulators 33. Arranged in front of each nozzle 30 is an annular counterelectrode 35 electrically insulated with respect to the metal wall of the container 25 by means of insulators 36. One metallic internal lead 32 and its associated counterelectrode 35 are connected to .the pair of terminals 36a, the other metallic internal lead 32 and its associated counterelectrode 35 being connected to the pair of terminals 37. Suitable arrangements for the obtention of ionized gas jets by means of such nozzles are described in Patent No. 2,837,654 and copending patent application Serial-No. 813,760 filed May 18, 1959. The designs and arrangements therein disclosed in greater detail may be employed, mutatis mutandis, for the present method.

The gas held in the container 40 is supplied, under adequate pressure, to the bores of the metallic internal leads 32, i.e. the nozzles 30, by lines 38 and the control unit 39.

' electrical jet discharge willibe set up by means of 21 voltage of e.g. 150 to 400 volts applied to the pairs of termina'ls 36 and 37,the said discharge causing the gas jets 29 to be strongly ionized. The proper. mode of operation for the obtention of such jet discharges has been described a in the above-mentioned references. Diiferent voltages may beapplied to the pairs of terminals. 36a and 37, in order to obtain jets of varying degrees of ionization.

Where titanium tetrachloride is employed as the initial material and ammonia as the reagent in the first stage, a

solid yellowish intermediate product 19 is obtained which' will change into a powdery product of a white orgrayish color under the action of the ionized atmosphere inthe.

or through a suitable separate gas supply line. A suitable exhausting .unit comprising a pump 63 and the separator 64 maintain a prescribed gas pressure in the container 50 via the exhaust connection 65, i.e. any excess of nitrogen and/or hydrogen or ammonia or protective gas is re moved. Portions of the" liquidtitanium tetrachloride which may have evaporated are removed through; the

connection 65 and condensed in the separator in order to be returned to the tank 54. Here, too', the volumes of U titanium tetrachloride and gaseousreagents should prefer ably be'so adjusted that the total volume of the substances supplied will forin a" solid' 'addition compound. If'this is the case, the pumppower requiredis comparatively small.

container 25. Analysis of this product has shown that it contains over 50% of the titanium ion originally present as free metallic titanium in powder 'forrn. The product obtained further containsuhydrazine chloride, ammonium chloride and a small. portion of titanium tetrachloride. If other metal halides are employed, an intermediate product having the general formula V Me (Ha)h.z(-N H is obtained in the first production stage H a halogen, N itrogen and H hydrogen, while the indices n, y and z express the integral numbers 1,

2, 3, 4-. Under the' action of an ionized atmosphere consisting of nitrogen and/ or hydrogen, this intermediate product'will yield a material which contains at least portions of 'the free metal Me; I

together with nitrogenous and/ or hydrogenous reagents. Me is a metal,

In the installation represented'in FIG. 1, the two stages i,

of the manufacturing processare each perf'or'm'ed'i'n separate reaction chambers, the first being performed in the container 13 and the second in container 25. With the installation for the performance of the method suitably designed, the two stages of the manufacturing process may be performed during the passage of the materials involved through a common reaction chamber, the first stage being performed'upstream of the second. FIG. 2 showsa'diagrammatic view of such aninstallation having a common reaction chamber. V

In'the installation according to FIG. 2 a common con ta'iner' 50'is' provided. The first stage of the manufacturing processiduring which the intermediary product is-obtained is performed in itsupper section 5 1., The solid intermediate product drops into the lower portionof the container and in so doing passes a zone 52 in which it is subjected to the action of an ionized atmosphere and in which the second stage of the manufacturing process is performed. Ali the lower end of the container 50, the

product 53 will collect, and contain at least a portio'n of free metal provided thata metal halide has been supplied as the initial material. 4 7

Titanium tetrachloride is again taken as one of the initial materials. It is a liquid 55'held in the. tank 54' and injected into the'upper portion 51 of the container'stl via the controlmember. 57 and a sprinkler-type multiple jet memberj58 under the pressure of a. protective gas sup- 7 the dimensions of the lateraltub'ular extensions 78 and f 79 are such as to ensure that the entirfe 'cros's-sectional' plied through line 56'. Arranged inthe cover59 of'the" supply line 62 via the control member 61. Nitrogen and hydrogen'or a compound containing nitrogen-and hydrogen such as ammonia gas is supplied through line 62. If

desired, a further. gaseous component may besupplied to the container 50 as a protective gas, either ,through line 62 or together with the liquid initial substance 54,

- container 51 besides this multiple jet member 58 is a gas I supply nozzle 60 which is .in'turn supplied by the gas portion 51 ofthe container 50 exhaust connection 65 and reach a zone '52 ofthe reaction container in which an ionized gas atmosphereis created This gas atmosphere. is obtained, irilt he plant represented in FIG. 2, by gas jets 166 and'67formed by'flie metallic" nozzle bodies 68" and 69 respectively fThese "nozzle bodies are'eacll providedwith a bore which-allows the gas supplied through lines .70 andf7lto emerge in the. A form oftwo gas jets.- In the present embodiment, both-'- nozzle bodies 68 and 69aresuppliedwith the same gas via a common control member 72. This'fi'need not be so, fortbo'th nozzle bodies maybe supplied separately! The control member 72 is connected to the mixing container 73' in which the gas or gas 'rnixture required for the jets 66 and67 is mixed; In'the present case, the mixture contains two'comp'onents suppliedto the container 73 via co'ntrol'r'n'embers 74 and 75 respectively, Theigasjets 66 and 67 should be formed 'by either nitrogen'orihydrof gen, or by a mixture of nitrogen and hydrogen or by ammonia. The use of a gas-mixture formedofammonia I NH;, and nitrogen N is particularly advantageous. :"Thc

metallicinozzle bodies 68 and'69 are arranged in insulated relationship in lateral tubular extensions 78"a'nd 79 at the container 50 by rneans of thejjin'sulating members '76 and 77, respectively.' Arranged closely in front of the mouth of the nozzle-type herein the nozzli'bodies' 68. I and ,69 are coun terelectrodesv 80 and 81 respectively passed, in insulateclrelationship, thro' lg fi the metalwall' of the tubular extensions 78and 79 by means ofinsulating'bodies 82 and 83.? The metallicinozzle body 68 and the counterelectrode 80 associated with it a're'con- I nected to the pair'of terminals 84, while, the-metallic nozz lebody. 69witl1its associated counterele'ct'rode -81fare" connected to the pairof terminalsq8 5: Set up across these pairs of terminals 84' and 85 is an electric field be-f tween the nozzle .bodyg68 and 69 respectively, an'dlthef counterelectrode 80 and 81' respectively; This-is prfeferspectively operates as the cathode.' 'The, gas jets]66 iand V 67 emergingfromjthe nozzle bores are stronglyioniz'ed provided thattheQvoltage at the pairs of terminals 841 and 85 is high enough, as has already been described inv the above-mentioned patents? The structuralldet'ailsof the designs disclosed in the said patents'and the measures described for the obtention of ionized gas jets'may here be applied mutatis mutandis.

The solid intermediate products obtained thefupper I I s'ink, under their own. 7 weight and aided by the gas flow, in the directionofthe The" nozzle boresiin'the nozz'lelbodies 68 a nd.69' an'd A area of the passage for'the-intermediate' products produced and falling in thespace 51 is uniformly and-as inv If desired, more than? two. opposed tubular extension 78"and 79"eacl1 having a'noz-' zle 68 and '69 mayjnaturally be providedin order lto en tensively ionized as possible".

. sure a sufficiently strong ionization in the'zonei 52. "1 By way ofexample', threev gas jetsradially converging may be i provided, which 'is' ofparticular advantage if they are supplied with the three phasevoltages of a three-phase 1 mains. '-It' is also possible, andadva-ntageous in? many cases, for the solid intermediate products dropping from the portion 51 to pass more than one zone 52, to which end a corresponding number of lateral nozzles must be arranged one beneath the other along the lower portion of the container 50. The two gas jets 66 and 67 may also be differently ionized if varying voltages are applied to the pairs of terminals 84 and 85. This possibility constitutes an advantage if each nozzle body 68 and 69 is provided with a separate gas supply and if different gases are employed for the jets 66 and 67, e.g. nitrogen for the one jet, and hydrogen for the other.

The powdery substances emerging from zone 52 and dropping will collect in the bottom portion of the container 50 and there form a powdery material 53 which is removed laterally from the container 50 by a worm conveyor 87 driven by the motor 86. Instead of the worm conveyor 87 here provided, any other suitable removal unit for powdery solid materials may be employed.

The production of the intermediate product in the first stage of the production process may, if desired, be performed under simultaneous electrical action. By Way of example, in the plant according to FIG. 1, the nozzle 12 forming the liquid jet may be incorporated in the cover of the container 13 by means of the insulating body 45. It is then possible by means of an electrical direct or alternating voltage applied to the pair of terminals 46 to set up an electric field between the metallic nozzle 12 and the inner wall of the metallic container 13, which may exercise an ionizing action and favorably affect the reaction between the reagents. A similar electrical action on the reaction performed in the first stage of the production process may also be obtained in a plant according to FIG. if. by way of example, is formed of an insulating material and a sufficiently strong electric field similar to that in the plant according to FIG. 1 is created between the metallic lines to the sprinkler-type multiple jet member 58 and the metallic wall of the container 50 on the one hand, and the metallic gas nozzle 60 and the wall of container 50 on the other. With the plant according to FIG. 2 it is further possible, if desired, to ionize only the gas entering via nozzle 60 and to dispense with an electric field between the jet member 58 and the metal container 50.

With the plant according to the embodiments shown in FIGS. 1 and 2, theionized gas atmosphere required in the performance of the second stage of the production process is formed by a so-called jet discharge which is a variant of the known gas and glow discharges respectively. Other electrical means for the ionization of the atmosphere to be traversed by the intermediate product during the second stage of the process may be employed, by way of example electrical spray or brush discharges as known in high-tension engineering and occasionally termed corona discharges. Furthermore, it is possible to effect ionization of the atmosphere by means of high-frequency gas discharges. Ionization of the atmosphere by means of electric arc discharges is possible as well, but suitable measures must be taken (e.g. the magnetic enlargement of the arc) in order to obtain an area as uniformly ionized as possible without allowing the intermediate products to be detrimentally affected by excessive temperatures. Ionization of the atmosphere by impacting, e.g. by intensive irradiation or by accelerated corpuscules, such as electrons or alpharays, is possible as well.

In the performance of the present method it has proved to be of importance for the degree of ionization of the gas atmosphere in the second stage of the production process to be adjusted to the type and volume of the intermediate product to be processed. An excessively intense ionization is just as disadvantageous as one too weak. It has proved of advantage in a plant according to FIG. 1 for the gas jets impinging on the intermediate product to consist of a mixture of NH and N since it seems that the desired chemical reactions of the intermediate product are favorably ina cover 59 of the container 50 6 fluenced by the simultaneous recombination of dissociated nitrogen. It is possible that this favorable influence depends on whether exothermic and endothermic chemical processes take place simultaneously of which the thermal balance is relatively adjusted at least substantially.

These intermediate products of the general formula Me (Hal) -2(N,,H e.g. TiCl -6NH are all products stable only in the absence of air. In air, and particularly in humid air, they will spontaneously decompose into metal oxides and/or metal hydroxides and ammonium chloride. These decomposition products can be processed into free metal, if at all, only with the greatest difiiculty.

It has now been found that calcining in an ammonia flow at higher temperatures, preferably at 900 to 1000 C. will produce a black substance from these intermediate products, which largely consists of TiNCl with the titanium compound and which is stable in air.

It has further been found that this TiNCl will dissolve in melted alkali titanium fluoride or, possibly, in other fused salt baths, e.g. in mixtures of anhydrous Mgcl SrCl CaCl etc. and that the metal can be obtained therefrom by fusion electrolysis. It is interesting to observe that titanium in a particularly pure form with at worst just traces of 0 or H, is obtained and that it possesses a low Vickers hardness.

Another preparation for electrolysis consists in fuming 01f calcined products of TiNCl with small volumes of concentrated nitric acid. The substance will then change into a compound of the formula TiN(N Which is also stable in air and has a whitish color of a slightly greenish cast.

This compound, too, can be dissolved in melted salts and pure titanium be obtained by fusion electrolysis.

Example 1 In a plant similar to that described in conjunction with FIG. 1, 10 gms. titanium tetrachloride was processed. The liquid titanium tetrachloride was atomized by means of nitrogen gas and mixed with 10 liters NH gas. A sulfuryellow solid addition compound was spontaneously formed, which chemical analysis proved to be TiCl -6NH The two initial products supplied were converted into the yellow intermediate product to the extent of nearly This intermediate product can be kept indefinitely under protective gas, in the present case under nitrogen gas, but will rapidlydisintegrate into a white compound consisting mainly of Ti0 in air. A small portion of NH Cl can also be detected.

. The yellow intermediate product was subjected to an ionized gas jet formed of nitrogen with the exclusion of air, i.e. under protective gas. The nozzle bore employed had an inner diameter of about 1 sq. mm. and the gas supply amounted to about 3-5 litres per minute. Between the counterelectrode 35 and the nozzle body 32 an electrical voltage of to 190 volts was applied and a negative pressure of about 30 mm. Hg maintained in the container 25. Under these circumstances, an electrical power of about 40 watts had to be supplied. The metallic nozzle body 52 formed the cathode of the glow discharge and, respectively, jet discharge set up. In view of the small quantity of intermediate product, it was piled only on one point of the conveyor belt 24 which was then placed underneath the ionized gas jet 29 and treated for four hours. The intermediate product changed its color from sulfur-yellow into white to grey.

After this processing period the product obtained was removed from the container 25 and dissolved in water, a deposit of about 2 gms. being filtered off, which proved to be free metallic titanium. The titanium yield in the present example thus amounted to about 80%. Titration of the filtered solution by means of an iodine solution according to Stolle indicated a content of 5.7 gms. hydrazine chloride (N H )Cl. The balance of the solution consisted of ammonium chloride NH CI and small quantity of unchanged titanium tetrachloride.

Examplev 2 anammonia flow and heated for one hour to 500 C. in

was passedvthrough. Thea calcining furnace While NH H product was freed from excess NH by passing through pure nitrogen and then charged into an electrolysis cell. under N protective gas. The said cell consisted of a graphite crucible which was kept at a temperature somewhat above the: melting temperature of Na TiF by'means of an electric heating coil. 1

From 20 gms. TiCl approx. l4fgms.calcinedproduct of a brown-yellow color was obtained which was disg solved in 150 gms; of an electrolyte of Na TiF keptat 850 C. After the calcined product had dissolved in the electrolyte, heating in the upper portion of the crucible was so reduced that face, and the N flow discontinued; Electrolysiswas performed at 4 volts and 3 amps. during 6 hours. after, a solid regulus of 3.6 gms. Ti hadformed at the bottom of the cell, corresponding to 72% of the Ti employed. t 1

We claim:

1. A process for producing metals of the class the halides of which form addition compounds with ammonia comprising forming an ammonia addition compound of a halide of a metal of said class and subjecting said am-;

monia addition compound-to the action of'an ionized atmosphere produced by an electrical-discharge to thereby produce free metal, said process being conducted under a protective atmosphere to exclude oxygen.

2. Aprocess as. claimed inclaim 1' wherein said free metal is a member selected from the titanium, vanadium, tin, aluminum andsilicon;

3. A process as claimed i'n'claim '1 wherein said ionized atmosphere contains at least one component selected'from the group consisting of hydrogen and nitrogen The inter- 1 a thin solid crustformed at the sur-;

group" consisting'rof charge to thereby produce free metal, said process beingconducted under a protective atmosphere to exclude oxygen.

- 5. A p'rocessas claimed'in claimAfwherein saidfree metal is a member selected from the group consisting of titanium, vanadium, tin,- aluminum and silicon.

6. A processas atmosphere contains at the group consisting-of nitrogen and=hydrogen.- I 7. A process as claimed in claim 4 wherein 'said gaseous member is ionized by an-are-free electric field.

8. A process: for producing titanium comprising'reacting titanium tetrachloride with ammonia in'a-firstreao 9 tion zone to form anqammonia .additioncompou'nd of monia addition compound to-ioni'zed nitrogen produced V by .an' electrical discharge in said second. reaction ,zone p I There said titanium tetrachloride, collecting said ammonia" addition compound, transferring said ammonia addition comwhereby free titaniumis produced, both ofsaid reaction zones'containing a protective atmosphere to preyent'oxygen from contacting said ammo'nia' addition compound;

9. A process'for producing a metal selectedtromlthe group consisting of titanium, vanadium, tin, aluminium. and silicon comprising reacting a V a first reaction zone with a gaseous member selectedfrom the group consistinglof ammonia and'a mixture ofnitro-i gen and hydrogen to form an ammonia addition compound of saidmetal halide; dition compound to second reaction zone subjecting said ammonia" addition compound to an .ionized'atmosphere containing at least one component selected from the groupconsisting of nitrogen..andthydrogen. to. thereby produce free" metal, said .ionizedfatmosphe're 'beingproduced' byan" electric discharge andboth of said reaction zones containing a protective atmosphere to prevent oxygen. from contacting V said ammonia. addition compound.

comprising reacting a halide of ametal-of said'class with a gaseous memberselected from the group consisting of ammonia anda mixture of nitrogen and hydrogen to-form an ammonia addition compound of said metal halide and subjecting said ammonia addition compound'to the" action of an ionized atmosphere produced'by an electrical dis- 9 References Cited in the file of this patent UNITED STATES PATENTS; 1,975,063 Malcolm .r "'Sept; 25, 1934, 2,002,003 .Eisenhut et a1. -May 21, 1935 2,724,692 Akerlof Nov. 22, 1955 2,952,599 'Suchet Sept 13, 19602 3,005,762 Penn- Oct. 24,. 1961 V FOREIGN PATENTS 795,416

claimedinclaim 4 wherein saidionized leastone component selected from halide of said jmetal in transferring sai'd ammonia ad-' a second reaction zone; and in said Great Britain 2 ,Ma 21', 1958 F 

1. A PROCESS FOR PRODUCING METALS OF THE CLASS THE HALIDES OF WHICH FORM ADDITION COMPOUNDS WITH AMMONIA COMPRISING FORMING AN AMMONIA ADDITION COMPOUND OF A HALIDE OF A METAL OF SAID CLASS AND SUBJECTING SAID AMMONIA ADDITION COMPOUND TO THE ACTION OF AN IONIZED ATMOSPHERE PRODUCED BY AN ELECTRICAL DISCHARGE TO THEREBY PRODUCE FREE METAL, SAID PROCESS BEING CONDUCTED UNDER A PROTECTIVE ATMOSPHERE TO EXCLUDE OXYGEN. 